Before Using Phentermine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it may do. This is a decision you and your doctor will make. For sympathomimetic appetite suppressants, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or amphetamine, dextroamphetamine, ephedrine, epinephrine, isoproterenol, metaproterenol, methamphetamine, norepinephrine, phenylephrine, phenylpropanolamine, pseudoephedrine, terbutaline, or other appetite suppressants. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Diet—You must follow a reduced-calorie diet while using an appetite suppressant in order to lose weight. Also, in order to keep the lost weight from returning, changes in diet and exercise must be continued after the weight has been lost.

Pregnancy—If a pregnant woman takes this medicine in high doses or more often than the doctor has directed, it may cause withdrawal symptoms in the newborn baby. Also, medicines similar to sympathomimetic appetite suppressants can cause birth defects in the newborn baby if a pregnant woman takes them in high doses. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—Diethylpropion and benzphetamine pass into breast milk. It is not known if other sympathomimetic appetite suppressants pass into breast milk. However, use of sympathomimetic appetite suppressants during breast-feeding is not recommended, because it may cause unwanted effects in nursing babies.

Children—Studies on these medicines have been done only in adult patients, and there is no specific information comparing use of sympathomimetic appetite suppressants in children with use in other age groups. The use of these medicines by children younger than 16 years of age is not recommended.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of appetite suppressants in the elderly with use in other age groups.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking appetite suppressants, it is especially important that your health care professional know if you are taking any of the following:
Amantadine (e.g., Symmetrel) or
Amphetamines or
Caffeine (e.g., NoDoz) or
Chlophedianol (e.g., Ulone) or
Cocaine or
Medicine for asthma or other breathing problems or
Medicine for colds, sinus problems, or hay fever or other allergies (including nose drops or sprays) or
Methylphenidate (e.g., Ritalin) or
Nabilone (e.g., Cesamet) or
Pemoline (e.g., Cylert)—Using these medicines with sympathomimetic appetite suppressants may increase the central nervous system (CNS) stimulant effects, such as irritability, nervousness, trembling or shaking, or trouble in sleeping
Appetite suppressants (diet pills), other or
Selective serotonin reuptake inhibitors (citalopram [e.g., Celexa], fluoxetine [e.g., Prozac], fluvoxamine [e.g., Luvox], paroxetine [e.g., Paxil], sertraline [e.g., Zoloft])—It is not known whether using two different appetite suppressants together or using a sympathomimetic appetite suppressant with a selective serotonin reuptake inhibitor is safe and effective. There have been some serious unwanted effects on the hearts of people who used two different appetite suppressants together
Monoamine oxidase (MAO) inhibitor activity (isocarboxazid [e.g., Marplan], isocarboxazid [e.g., Marplan], phenelzine [e.g., Nardil], procarbazine [e.g., Matulane], selegiline [e.g., Eldepryl], tranylcypromine [e.g., Parnate])—Do not take an appetite suppressant while you are taking or less than 14 days after taking a monoamine oxidase (MAO) inhibitor . If you do, you may develop sudden extremely high blood pressure
Tricyclic antidepressants (amitriptyline [e.g., Elavil], amoxapine [e.g., Asendin], clomipramine [e.g., Anafranil], desipramine [e.g., Pertofrane], doxepin [e.g., Sinequan], imipramine [e.g., Tofranil], nortriptyline [e.g., Aventyl], protriptyline [e.g., Vivactil], trimipramine [e.g., Surmontil])—Using these medicines with sympathomimetic appetite suppressants may cause high blood pressure or irregular heartbeat

Other medical problems—The presence of other medical problems may affect the use of appetite suppressants. Make sure you tell your doctor if you have any other medical problems, especially:
Alcohol abuse (or history of) or
Drug abuse or dependence (or history of)—Dependence on appetite suppressants may be more likely to develop
Type 2 diabetes mellitus—The amount of insulin or oral antidiabetic medicine that you need to take may change
Epilepsy—Diethylpropion may increase the risk of having seizures
Family history of mental illness—Mental depression or other mental illness may be more likely to occur
Glaucoma or
Heart or blood vessel disease or
High blood pressure or
Mental illness or
Overactive thyroid—Appetite suppressants may make the condition worse
Kidney disease—Higher blood levels of the appetite suppressant may occur, increasing the chance of serious side effects